Traffic signal lamp



Aug. 13,1935. LE ROY WOTTRING TRAFFIC SIGNAL LAMP Filed 001;. 15, 1929 I Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE 4.- Claims.

This invention relates to trafllc signal lamps and particularly to trailic signal lamps as employed for the control or traific at street intersections.

One of the'objects of this invention is to provide a trafllc signal lamp of improved construction of the type employing a lens, a lamp and a reflector.

Another object is to provide a trafiic lamp of the class specified, in which fogging of the lens and reflector is prevented.

Another object is to provide a trafiic signal lamp of this class in which the so-called phantom illumination of the lens by light from the sky is prevented.

Another object is to provide a traflic lamp of this class in which the lens, lamp and reflector may be sealed to render them dust and moisture proof and to maintain them clean and efficient.

Another object is to provide a traflic signal lamp having an improved light reflecting element. A

Another object is to provide a traflic signal lamp having an improved light transmitting lens.

Another object is to provide a traffic signal lamp having an improved mounting for an electric lamp bulb. l

Another object is to provide a trafiic signal lam requiring the minimum of attention and care to keep it clean and efi'icient and requiring the minimum of replacement of parts. j

Another object is to provide a traflic signaljlamp having improved lens illuminating and light projecting characteristics whereby it may convey trafiic signals to traflic in an improved and highly efficient manner.

Another object is to provide a tramc signal lamp which will be simple and cheap to construct and assemble and which will be efllcient in operation.

Other objects of this invention will be apparent to those skilled in this art.

My invention is fully disclosed in the following description and taken in connection withthe accompanying drawing, in which:-

Fig. 1 is a perspective elevational view of a complete four-way traflic signal lamp as adapted to be suspended over a street intersection and embodying my improved traflic signal lamp;

Fig. 2 is a cross-sectional side view of one of the signal lamp units of the lamp structure of Fig.

Fig. 3 is a horizontal sectional view taken from the plane 3 of Fig. 1 with parts below the sectional plane omitted for simplicity and with some of, the parts in diflerent positions.

Referring to the drawing, I have shown generally at l a main frame or housing of a tramc lamp. The housing I is composed of four vertical sides or panels 2, each provided with three circular apertures 3 in which the elements of. a traffic signal lamp are mounted. Associated with each aperture and signal lamp is a hood or visor 4 hinged as at 5 to the main housing. As shown in Fig. 3, the panels 2 are all similar or alike and each panel is provided at one edge thereof with an inwardly directed flange or with a plurality of lugs 6 and each panel 2 overlaps the lugs 6 of the next adjacent panel in one direction around the housing. Of the hinges 5, the stationary portions 1 thereof are bolted to the housing adjacent the corners thereof shown in Figs. 1 and 2 and bolts 8 pass through a foot 9 on the hinge element 1, through perforations in the panel 2 and throughthe lugs 6 andbolt these three parts rigidly together. Thus, by a very simple construction easily assembled, the panel form structure is provided.

The housing has also a bottom Ill and a top or cover ll secured to the panels in any suitable manner, as by bolts I2-l2 and I3-I3, respectively. Any suitable means, such as the means indicated at It, may be secured to the cover II to support or suspend the lamp over a street intersection; and by means of a conduit outlet l5, electric connections may be made to the interior of the housing to illuminate lamps therein, to be described. At each of the apertures 3, the panel is formed with an inwardly directed annular rim !6 tapering inwardly and at its inner periphery provided with a radially directed annular flange [1. The annular flange I1 is provided at spaced intervals with tapped holes l8 for screws l9. Clamped against the flange I1 is an outwardly radially disposed annular flange 20 of a sheet metal reflector 23, the clamping force being provided by the screws l9 and by perforated clips 2| through which the screws are passed and which project inwardly over the flange 28. Preferably, a gasket of suitable material such as cork 22 is placed between the flanges l1 and 20 to effect an air tight seal at the periphery of the reflector 23.

The sheet metal reflector 23, as indicated in Fig. 2, is of generally bowl shape. The cross-sectional profile thereof preferably follows the curvature of a parabola. I find that the improved results obtained with the signal lamp of my invention are in a large measure due to employing a reflector 23 of parabolic profile, flatter or with a more distant focus than is commonly employed in lamps of this kind. The reflector which I employ is preferably made of sheet copper and chromium plated. The chromium metal plate on the concave face of the reflector 23 is highly polished to a mirror like surface and besides providing a very superior reflecting surface renders the polish thereof durable. The reflecting quality of the'reflector is not easily deteriorated either by atmospheric conditions or chemical action thereof, nor even by wiping and cleaning of the same by an attendant, these advantages, as will be understood resulting from the property of great hardness of the metal chromium.

Furthermore, this reflector of my invention is more eflicient as a reflector of light than reflectors heretofore employed, such as glass reflectors of mirror construction provided with a reflecting medium on their convex surface, because with such glass reflectors, the light rays must pass through the glass to the reflecting medium and then pass through it again after being reflected whereby much of the light energy is absorbed and lost. In my improved reflector on the other hand the light is reflected directly from the concave surface.

Formed in the wall of the reflector and sealed therein is a generally tubular lamp socket 24 in the interior end of which may be screwed a lamp bulb 25 and in the exterior end 26 thereof may be mounted the usual or any suitable receptacle and plug for conducting electric current to the bulb. It will be observed that the longitudinal axis a: of the socket 24 is disposed at an angle to the horizontal; and while this angle may be varied between limits, I prefer an angle of about 45. The socket 24 is positioned in the reflector so that the filament 21 of the lamp may be located at the focus of the parabola.

One of the advantages of mounting the lamp in this angular or'inclined position instead 9f in the more usual horizontal position in signal lamps of this general class, is that the heat from the lower portions of the filament 21 is conducted away from the filament by the circulation and convection of the gaseous contents of the bulb and thence is radiated away through the walls of the bulb and is not carried to upper portions of the filament and does not therefore overheat and prematurely burn out the upper portions of the filament. At the same time, the well known advantages of positioning the bulb with the free end or the end opposite the socket directed away from the reflector generally are retained.

The lamp lens 28 is mounted in a combined cover and visor 29. The cover comprises an annular flange 30 provided on its inner face with an annular recess 3| in which is positioned a sealing gasket of suitable material such as cork 32. The

gasket is engaged by an annular bead 33 outwardly projecting from the panel 2. Thus, by

clamping the flange 30 toward the panel 2, in a manner to be described, an air tight joint is effected between the flange and the panel. Inwardly with respect to the flange 30 is an inwardly directed annular flange 34, upon which, by means of clips 35 and screws 36passing therethrough and threaded into the flange 30, a lens 28 is clamped. The lens is generally of bowl shape, having a cross-sectional profile of pre-selected curvature, preferably circular, and provided at its periphery with a flange 39 adapted to seat upon the flange 34. Between the flange 39 of the lens and the flange 34 of the cover, a sealing gasket 36 of cork or other suitable material is placed to provide an air tight joint. The convex surface of the lens 28 is preferably smooth.

The concave face thereof is rendered light diffusing by suitable surface texture. Any known or suitable surface condition may be given to the concave lens face, to render it light diffusing, but I prefer to provide it, in the molding thereof, with small granular projections, of such size and shape that the concave surface resembles in structure very coarse sand paper. The material of the lens 28 is preferably glass of color suitable for the purposes to which the signal lamp is put.

Extending outwardly in a generally horizontal direction from the flange 30 is a hood or visor 4. The upper portion of the visor preferably slopes downwardly and the sides thereof are gradually shortened horizontally along any pre-selected curve as at 38 and at the lower side the visor or hood is reduced to a very short small horizontally projecting flange 50.

The flange 30 has formed therewith hinge elements 40-40 adapted to be connected to the above described stationary hinge element 1 by suitable pintles whereby the entire cover above described, exterior with respect to the panel 2, may be hingedly rotated outwardly, as indicated in Fig. 3, to give access to the bulb 25, reflector 23 and lens 28. When the cover is in the position shown in Fig. 2, it may be clamped to seal it thereon, as above described, by suitable pivoted clamping dogs 4| overhanging the periphery of the flange 36 and thumb nuts 42 for securing them in 1 position. To open the lamp as above described the scribed, the reflector and lens'are sealed against the entrance of both moisture, dust or dirt, with the very apparent attendant advantages.

I 3y the employment of a reflector 23 of relatively flat parabolic form, light rays from the 'sky= which enter the lamp under the outer edge of the visor 4, will be reflected back toward the sky ,or toward the ground abruptly and will not be reflected horizontally or downwardly at relatively small angles through the lens 28 to present to the traflic a false or phantom illumination of the lens 28 as frequently occurs in prior trafiic lamps. In some lamps as heretofore constructed of which I have knowledge, rays entering under the visor strike the moresharply curved reflector upon the lower portions thereof and are reflected upwardly to upper portions thereof and thence reflected outwardly and downwardly in directions visible to trafiic producing the phantom effect above referred to.

In this respect, referring to the drawing, Fig. 2,

, sun rays entering the lamp horizontally, as at reflected sharply downwardly and not visible, when the rays strike the upper half of the reflector. A ray coming from an angle above the horizontal, as at 65, and striking the reflector below the focus will be reflected upwardly, and therefore not visible.

Thus, by employing a reflector of relatively flat parabola and with the focus thereof substantially at the forward periphery of the reflector, direct rays from the sun will be scattered and diifused and reflected in directions which will render them not visible to traffic, except perhaps traflic almost directly under the lamp, which of course is negligible in this instance.

Also, as will be understood, horizontalor very nearly horizontal sun rays impinging on points of the reflector above and very near its axis will be reflected downwardly and may be visible to traflic, particularly trafllc remotely disposed from the lamp, but as this condition is seldom encountered in practice, it is negligible.

By the employment of a lens 28 having a smooth surface on the outside and the pebbled or sand surface on the inside, the lens when illuminated by the bulb 25 presents to the traflic a solid disk of uniformly diffused color glow without glare, and due to the elimination of the phantom effect, as above described, when the bulb 25 is de-energized the color of the lens 28 substantially completely disappears, thus rendering the signal lamp positive in action and giving it the maximum effectiveness in controlling traffic. I have shown and described my invention as applied to a type of traflic lamp adapted to be suspended over a street intersection, but it will be apparent that my invention may be practiced with all of its advantages in other types of Imps, such, for example, as that which is to be suspended or supported at a corner or at corners of a street intersection.

My invention is not limited to the exact construction shown and described, inasmuch as many changes and modifications thereof may be made within the scope of my invention without departing from the spirit thereof or sacrificing its advantages.

I claim:

1. In a lamp of the class described, a generally parabolic reflector having a forward terminal periphery which, when the reflector is disposed with the axis horizontal, has at least asubstantial part of the forward periphery thereof disposed in a plane at right angles to the axis and containing the focus, a lens having a light transmittingportion of substantially the same area as the projected area of the reflector, means supporting the lens with the periphery of said light transmitting portion spaced axially from the periphery of the reflector, an electric lamp between the reflector and the lens having a. filament substantially at the focus, whereby a horizontal sun ray passing through the lens and impinging upon the reflector at any point will be reflected through the focus and out of the reflector in a divergent direction from the axis; and a direct ray imping-r ing upon a point of the reflector above the axis from a direction at an angle above the horizontal will be reflected across the reflector behind the focus and out of the reflector in a downwardly divergent direction from the axis; and a direct sun ray impinging upon a point of the reflector below the axis from a direction at an angle to the horizontal will be reflected out of the reflector in an upwardly divergent direction from the axis.

2. A lamp of the class described and as set forth in claim 1, and in which a visor extends forwardly above the reflector to exclude all of the direct sun rays except the horizontal and those at relatively small angles above the horizontal.

3. In a lamp of the class described, a generally parabolic reflector having a forward terminal periphery which, when the reflector is disposed with the axis horizontal, has at least a substantial part of the forward periphery thereof disposed in a plane at right angles to the axis and containing the focus, a tubular element extending forwardly from the peripheral portion of the reflector, a lens having a light transmitting portion supported by a peripheral portion thereof adjacent a forward portion of the tubular element and thereby being spaced axially from the reflector, an electric lamp between the reflector and the lens having a filament substantially at the focus, whereby a honzontal sun ray passing through the lens and impinging upon the reflector at any point will be reflected through the focus and out of the reflector in a divergent direction from the axis; and a direct ray impinging upon a point of the reflector above the axis from a direction at an angle above the horizontal will be reflected across the reflector behind thefocus and out of the reflector in a downwardly divergent direction from the axis;

and a direct sun ray impinging upon a point i jof the reflector below the axis from a direction at an angle to the horizontal will be reflected out of ithe reflector in an upwardly divergent direction rays except the horizontal and those at relatively small angles above the horizontal.

LE ROY WOT'I'RING. 

